HELP APPRECIATED!

We took a chance and bought a Dodge Caravan that has engine issues.
The person that owned it, was driving it on the highway and it just quit. When he went to start it, it did not run on all it's cylinders.
It smokes out the exhaust, smells like it is running rich, and you can smell gasoline. Exhaust also comes out where the oil goes in.
It does not hold idle unless you have the excellerator down. Refuses to go more than 1-2 feet in gear. We are hoping it is a simple problem. We attempted to check the spark and it seems *Not for sure* that only a few of the wires are producing spark. We had the coil pack checked. (AutoZone) they said it was OK.